1. Field of the Invention
The present invention relates to a nozzle error correction method and an image-forming apparatus using the same. More particularly, the present invention relates to a nozzle error correction method and an image-forming apparatus using the same that detects an error pixel including an error nozzle and adjusts a value of the error pixel to correct the error nozzle.
2. Description of the Related Art
An ink-jet image-forming apparatus is a device for printing desired images on paper by firing ink through nozzles disposed in an array on a head. The nozzles are mechanical parts which can cause errors, such as a different ink-firing amount from that required in a design, or no ink firing from the nozzles. The errors from the nozzles result from defects during the image-forming apparatus manufacturing process or aging caused by fatigue. As a result, the nozzle error causes a degradation of quality printout images.
The conventional nozzle error correction method detects error nozzle position information and corrects the error nozzle by the head controller using the error nozzle position information. Such nozzle error correction method includes moving the head mechanically and placing a normal nozzle at the error nozzle position, controlling the time for an error nozzle to fire ink, and so on.
FIGS. 1A and 1B are views for explaining a conventional nozzle error correction method for mechanically moving the head and placing a normal nozzle at an error nozzle position. FIG. 1A is a view that illustrates all normal nozzles disposed in a row, and FIG. 1B is a view that illustrates nozzles disposed in a row and having an error nozzle therein.
In FIG. 1A, if an error nozzle is not detected, the head with a series of nozzles disposed thereon prints images by moving in a perpendicular direction to a paper movement.
In FIG. 1B, if an error nozzle is detected, the head moves in a perpendicular direction to a paper movement so that the normal nozzle is disposed at the position of the error nozzle and fires ink instead of the error nozzle.
In the conventional nozzle error correction method, a head-controlling circuit uses error nozzle position information and corrects the error nozzle. However, according to the conventional method, the head is moved in order for the normal nozzle to fire ink instead of the error nozzle. As a result, the normal nozzle accumulates fatigue and will likely become an error nozzle.
Further, the conventional nozzle error correction method using the head reduces print speed and shortens the life span of the head, since mechanical and image printout operations are required for the head.
Further, the nozzle error correction method that mechanically moves the head cannot be applied to image-forming apparatuses using a full-type head. The full-type head has a fixed position and performs printing by using a number of nozzles that correspond to a paper size. Thus, the mechanical moving of the head in the nozzle error correction method cannot be applied thereto.
Accordingly, there is a need for an improved nozzle error correction method that corrects an error nozzle caused by an output error pixel of the error nozzle.